Systems, methods and devices for 3d rolling of multi-gauge parts

ABSTRACT

Disclosed are metalworking rollers for fabricating multi-gauge sheet metal parts, methods for making and methods for using such rollers, and rolling mill machines employing variable-radius metalworking rollers for fabricating multi-gauge metal components. A metalworking roller for a rolling mill machine is disclosed. The metalworking roller includes a cylindrical roller body that rotatably and drivingly connects to the rolling mill machine. An outer diameter surface spanning around the roller body circumference includes an outermost peak region and an innermost valley region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body. During operation of the rolling mill machine, the outermost and innermost regions of the roller body&#39;s outer diameter surface sequentially press against and thereby modify the gauge of a metal workpiece. Each region has a respective transverse width and circumferential length extending across and around the longitudinal length and circumference, respectively, of the roller body.

INTRODUCTION

The present disclosure relates generally to metalworking processes for manufacturing metal components. More specifically, aspects of this disclosure relate to systems, methods and devices for forming multi-gauge parts from metal sheet stock or metal blanks.

Iron, steel, aluminum and other metallic materials are used for manufacturing a vast array of modern products. Many tools, automobiles, bridges, trains, airplanes, buildings, and boats all depend on metal parts to make them robust and economical. During the early metal processing stages of manufacturing, large metal slabs or bar stock (known as “billets”) are formed from molten metal, for example, using continuous casting or other applicable metalworking process. For sheet stock, the slab/billet of metal generally undergoes “hot rolling” to obtain a continuous metal sheet of a relatively medium thickness, which is then rolled into spools or coils. Hot rolling is a process by which raw purified metal is passed, pressed, or drawn through a set of work rolls in a continuous and generally linear fashion, where the temperature of the metal is above its recrystallization temperature. Hot rolling permits large deformations of the metal to be achieved with a relatively low number of rolling cycles.

For ferrous metals, aluminum alloys and copper, the spool may then be unrolled for chemical descaling—referred to colloquially as “pickling”—during which the surface is treated with a hydrochloric acid solution (known as “pickle liquor”) in order to remove impurities, contaminants, scale, stains, and rust. After chemical pretreatment, the sheet may then be subjected to “cold rolling” to obtain sheets with a desired final thickness. During cold rolling, the metal sheet stock is passed, pressed, or drawn through rollers with the metal at a temperature below its recrystallization temperature. The cold rolling process may be employed to increase the yield strength and stiffness of the material by introducing defects into the metal's crystal structure. Upon completion of the cold rolling operation, the metal sheet is often heat treated through annealing, tempering, etc., to obtain certain desired mechanical characteristics, machinability, etc., and again rolled into a spool for packaging and shipping.

Many of the parts used to fabricate the chassis support frame, body-in-white (BIW) frame and outer body panels of an automobile are formed from metal sheet stock. For example, once the metal spool has been successively unrolled, suitably degreased and surface treated, it is cut or shaped into part blanks using, for example, a blanking press. An array of blanks or a single blank may be die cut into a workpiece having the general peripheral dimensions of the object to be manufactured, e.g., in a manner often analogized to cookie cutting. The part blanks may thereafter be exposed to other forming and treating processes before the parts are assembled and combined into the vehicle frame and body. Each blank may be embossed with a desired surface texture via machining, laser processing, chemical etching, stamping, or peening. If a specific cross-section is desired, such as the box-shaped or U-shaped cross section of a chassis side rail or BIW pillar, the blank may be passed through a roll forming machine.

SUMMARY

Disclosed herein are 3-dimensional (3D) metalworking rollers for fabricating multi-gauge parts from sheet metal, methods for making and methods for using such 3D rollers, and rolling mill machines employing variable-radius 3D metalworking rollers for fabricating multi-gauge vehicle components. By way of example, and not limitation, there is presented a variable-radius roller that is molded, machined, or otherwise fashioned with a recessed, circumferentially elongated region for forming variable gauge parts from metal sheet stock and metal blanks. The depth of this region may vary along the circumference of the roller to thereby vary the gauge of each part along the length of the blank. As an example, the recessed region may include a series of descending and ascending stepped segments to sequentially increase and decrease the gauge of the part. Transition sections interconnecting regions of different radii may comprise rounded or low-angle transition surfaces (e.g., less than 45 degrees from a plane tangent to the roll surface) to provide a gradual, rather than abrupt, change in gauge. While available as an optional feature, the 3D roller does not merely generate superficial texturizing or discrete grooves in the sheet metal; rather, the 3D roller modifies the cross-sectional thickness of the workpiece by creating one or more longitudinally elongated raised areas. The circumference of the 3D roller may be sized to coincide with the length of the blank.

Attendant benefits for at least some of the disclosed concepts include the ability to quickly and continuously generate variable gauge parts from metal sheet stock and metal blanks such that final part gauges approach or achieve optimal gauges as determined by multi-disciplinary design optimization (MDO) and/or gauge optimization techniques. Disclosed concepts allow metal sheet stock/metal blanks to be rolled to a set of predetermined final gauges using a custom 3D roller to create blanks with thickness variations in both the X and Y-directions (e.g., from leading-to-trailing edges, and from left-to-right transverse edges). Other benefits may include the ability to achieve similar thickness changes to those found in tailor welded blanks without adding heat affected zones near the welds and allow for a much more benign transition between thicknesses. Additionally, several gauges may be achieved for a single part that would more closely align to the optimized gauges found through MDO techniques. Disclosed approaches to part gauge optimization can be used to consolidate parts, e.g., without requiring multiple alloys or multiple joined pieces of the same alloy.

Aspects of the present disclosure are directed to variable-radius metalworking rollers for introducing multiple gauges into single-layer metal sheet stock or individual single-layer metal blanks. In an example, there is disclosed a metalworking roller for a rolling mill machine operable to change the gauge of a metal workpiece. The rolling mill machine includes a drive mechanism, a roll stand, and other optional peripheral hardware, such as feed rollers, backing rollers, pillow blocks, conveyors, sensors, wiring harnesses, etc. The metalworking roller includes a cylindrical roller body that rotatably attaches (e.g., via bearings and keyed shaft) to the roll stand, and drivingly connects (e.g., via gear train or drive chain) to the drive mechanism. The roller body's outer diameter (OD) surface, which spans continuously around the roller body circumference, includes an outermost “peak” region and an innermost “valley” region that is recessed radially inward from the outermost peak region and elongated circumferentially around the roller body. The roller body's OD surface may also include other recessed regions, such as an intermediate “plain” region that is recessed radially inward from the outermost peak region, but offset radially outward from the innermost valley region. These radially offset regions—the outermost, intermediate and/or innermost regions—sequentially press against and thereby modify the gauge of the metal workpiece.

Other aspects of the present disclosure are directed metalworking systems, apparatuses, and devices (collectively “machines”) for introducing a non-uniform longitudinal thickness into single-layer metal sheet stock or individual sheet metal blanks. Disclosed, for example, is a rolling mill machine for changing the gauge of a sheet metal workpiece. The rolling mill machine includes a roll stand, a drive mechanism operatively connected to the roll stand, and a subjacent support roller rotatably mounted to the roll stand. A metalworking roller is drivingly connected to the machine's drive mechanism and rotatably mounted onto the roll stand juxtaposed with the subjacent roller. The metalworking roller has an elongated cylindrical roller body with an OD surface that spans continuously around the circumference of the roller body. This OD surface is molded, machined or otherwise fabricated with an innermost valley region that is recessed radially inward from an outermost peak region. The outermost and innermost regions each have a respective surface area and a respective radial thickness that is substantially constant across the length and width of that surface area. During operation of the rolling mill machine, the metalworking roller is driven such that the outermost and innermost regions sequentially press against and thereby reduce the gauge of the sheet metal workpiece to introduce two or more different gauges into the workpiece.

Additional aspects of this disclosure are directed to methods of making and methods of using variable-radius metalworking rollers for introducing multiple gauges into metal sheet stock or sheet metal blanks. For instance, a method is disclosed for changing a gauge of a metal workpiece via a rolling mill machine with a metalworking roller. The method includes, in any order and in any combination with any disclosed options: feeding the metal workpiece into engagement with the metalworking roller, which includes a cylindrical roller body with an outer diameter surface that spans continuously around the circumference of the roller body, the outer diameter surface including an outermost peak region and an innermost valley region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body; and, rotating the metalworking roller via the drive mechanism such that the outermost peak region and the innermost valley region sequentially press against and thereby modify the gauge of the metal workpiece.

The above summary is not intended to represent every embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel aspects and features set forth herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of representative embodiments and representative modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and subcombinations of the elements and features presented above and below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated perspective-view illustration of a representative rolling mill machine with a representative variable-radius 3D metalworking roller modifying the gauge of sheet metal workpiece in accordance with aspects of the present disclosure.

FIG. 2 is an enlarged perspective-view illustration of a select portion of the representative metalworking roller of FIG. 1.

FIG. 3 is an enlarged perspective-view illustration of a select portion of the representative sheet metal workpiece of FIG. 1.

The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the appended drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, subcombinations, permutations, groupings, and alternatives falling within the scope and spirit of the disclosure.

DETAILED DESCRIPTION

This disclosure is susceptible of embodiment in many different forms. There are shown in the drawings and will herein be described in detail representative embodiments of the disclosure with the understanding that these representative embodiments are to be considered an exemplification of the principles of the disclosure and are not intended to limit the broad aspects of the disclosure to the illustrated embodiments. To that extent, elements and limitations that are disclosed, for example, in the Abstract, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise. For purposes of the present detailed description, unless specifically disclaimed: the singular includes the plural and vice versa; the words “and” and “or” shall be both conjunctive and disjunctive; the word “all” means “any and all”; the word “any” means “any and all”; and the words “including” and “comprising” and “having” mean “including without limitation.” Moreover, words of approximation, such as “about,” “almost,” “substantially,” “approximately,” and the like, may be used herein in the sense of “at, near, or nearly at,” or “within 3-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof, for example.

Referring now to the drawings, wherein like reference numbers refer to like features throughout the several views, there is shown in FIG. 1 a representative rolling mill machine, which is designated generally at 10 in the Figures and represented herein for purposes of description by various select components. Many of the novel aspects and features of the present disclosure will be described herein with reference to the architecture illustrated in FIG. 1 as an exemplary application with which these aspect and features can be practiced. It will be understood, however, that the disclosed concepts are by no means limited to the particular constructions illustrated in the drawings. Rather, aspects and features of the present disclosure may be implemented for forming metal workpieces of other configurations, and may be incorporated into other metal forming apparatuses and operations without departing from the intended scope and spirit of this disclosure. Lastly, the drawings presented herein are not necessarily to scale and are provided purely for instructional purposes. Thus, the specific and relative dimensions shown in the drawings are not to be construed as limiting.

Operating as a forming apparatus for hot rolling or cold rolling metal parts, such as low carbon steel or aluminum alloy automobile body panels or BIW frame sections, the rolling mill machine 10 selectively compresses and thereby introduces multiple gauges into single-layer metal sheet stock or single-layer metal blanks, both of which are represented in the drawings by an individual sheet metal workpiece 12. According to the illustrated example, the rolling mill machine 10 is composed of a structurally resilient support frame 14, more commonly known to those skilled in the art as “roll stand,” for providing functional support for elements of the machine 10. Operatively connected to the support frame 14 is drive mechanism 16, which may be in the nature of a single or twin-drive system each composed of a geared-down electric stepper motor or a low-speed, high-toque hydraulic motor. A subjacent support roller 18 is rotatably mounted in a generally horizontal fashion to the roll stand 12, at the proximal end of a workpiece transfer platform 20.

Operation control of the rolling mill system 10 is provided, at least in part, by a system controller, depicted in FIG. 1 in an exemplary embodiment as a micro-processor based electronic control unit (ECU) 22 having one or more processors, including but not limited to a master processor, a slave processor, and a secondary or parallel processor, as well as a suitable amount of memory, such as a volatile memory (e.g., a random-access memory (RAM)) and a non-volatile memory (e.g., an EEPROM). Only select components of the rolling mill machine 10 have been shown and will be described in detail herein. Nevertheless, the machine 10 discussed herein can include numerous additional and alternative features, and other well-known peripheral components, for example, for carrying out the various methods and functions disclosed herein without departing from the intended scope of this disclosure. It should also be appreciated that the machine 10 may be indicative of a standalone device, a section of a larger rolling mill apparatus, or one part of a multi-stand tandem mill system.

To generate multi-gauge metal parts, the rolling mill machine 10 employs a variable-radius (3D) metalworking roller 24 that is rotatably mounted to the roll stand 14, e.g., via counterposed bearing blocks and a mating keyed shaft (not shown), juxtaposed with and generally parallel to the subjacent roller 18. The metalworking roller 24 includes an elongated, right-circular cylindrical roller body 26 that is drivingly connected to the mill's drive mechanism 16, e.g., via gear train, drive shaft, drive belt/chain (not shown) or other operative connection. For at least some applications, it is desirable that the roller body 26 be fabricated from a wear-resistant and corrosion-resistant material with sufficient structural resilience to cold/hot roll a continuous feed of metal sheet stock or metal blanks, e.g., at operating pressures in a range of approximately 1,500 to 4,500 psi. By way of non-limiting example, the roller body 26 may be cast and precision machined from ultra-hard, alloyed, chrome-plated or ceramic-coated steel with a smooth (“mirrored”) or texturized (“roughed”) exterior. Optionally, the illustrated rollers may take on other geometries, dimensions, and/or orientations from that which are shown in the drawings. For practical purposes, it may be pragmatic to employ a series of variable-radius metal forming rollers—progressive rollers operating in stages—for a single part to achieve a requisite set of gauges.

With collective reference to both FIGS. 1 and 2, the metalworking roller 24 has an outer diameter (OD) surface 28 that spans continuously around the circumference of the cylindrical roller body 26. Fabricated as a variable-radius construction, this metalworking roller 24 is molded, machined, or otherwise fashioned such that the OD surface 28 is an aggregation of various surface regions each having a distinct radial thickness with respect to the roller body 26. In accord with the illustrated example, the total surface are of the OD surface 28 is defined by three distinctly shaped and distinctly sized regions—an outermost “peak” region 30, an intermediate “plain” region 32, and an innermost “valley” region 34. Recognizably, the number, shape, size, orientation and location of each region can be varied from what is portrayed in the drawings. As shown, a portion of the outermost peak region 30 has a distinct transverse width W_(OR) that extends the entirety of (i.e., is substantially coextensive with) the longitudinal length L_(RB) of the cylindrical roller body 26. In this regard, a portion of the outermost region 30 has a distinct circumferential length L_(OR) extending continuously around the entirety of the outermost circumference C_(RB) of the roller body 26. Lastly, the outermost region 30 has a distinct surface area A_(OR) and a distinct radial thickness R_(OR) that is constant along the length and width of this surface area A_(OR). When the metalworking roller 24 is operatively engaged with and compresses a blank 12, as discussed further below, outermost region 30 will generate a correspondingly shaped “thin” gauge region 36 with the overall smallest gauge.

Innermost valley region 34 is recessed radially inward from both the outermost peak region 30 and the intermediate plain region 32, extending circumferentially around a portion of the roller body 26. By way of example, and not limitation, the innermost region 34 has a distinct circumferential (arc) length L_(IR) that extends, e.g., about 10-50% or at least 20% or approximately 25% around the circumference C_(RB) of the roller body 26. Moreover, the innermost region 34 has a distinct transverse width W_(IR) that extends, e.g., about 20-70% or at least 30% or approximately 50% of the longitudinal length L_(RB) of the cylindrical roller body 26. The surface area A_(IR) of the innermost region 34, which is less than the surface area A_(OR) of the outermost region 30, has a distinct radial thickness R_(IR) that is less than the outermost radius R_(OR) and is constant along the length and width of surface area A_(IR). When the metalworking roller 24 is operatively engaged with and compresses a blank 12, the innermost region 34 will generate a correspondingly shaped “thick” gauge region 38 with the overall largest gauge. It may be desirable, for at least some embodiments, that the length L_(IR) and width W_(IR) of the innermost region 34 be sufficiently sized to ensure that the thick gauge region 38 covers a sufficiently sized portion of the workpiece 12 to exhibit isotropic properties, rather than being a mere discrete indentation or surface texturization exhibiting anisotropic properties.

The roller body's OD surface 28 may be formed or precision machined to include one or more additional or alternative recessed regions, such as the intermediate plain region 32 that is recessed radially inward from the outermost peak region 30, but offset radially outward from the innermost valley region 34. Like the valley region 34, the plain region 32 extends circumferentially around some, but not all, of the roller body 26. In the same vein, the plain region 32, like the valley region 34, extends transversely across some, but not all, of the roller body's longitudinal length. According to the illustrated example, the intermediate region 32 has a distinct circumferential (arc) length L_(ITR) that extends, e.g., about 30-80% or at least 40% or approximately 50% around the circumference C_(RB) of the roller body 26. Additionally, the intermediate region 32 has a distinct transverse width W_(ITR) that extends, e.g., about 40-90% or at least 50% or approximately 75% of the longitudinal length L_(RB) of the cylindrical roller body 26. This intermediate plain region 32 has a distinct surface area A_(ITR) that is greater than the surface area A_(IR) of the innermost region 30, but less than the surface area A_(OR) of the outermost region 28. Plain region 32 has a distinct radial thickness R_(ITR) that is greater than the innermost radius R_(IR) and is constant along the length and width of the surface area A_(ITR). When the metalworking roller 24 is operatively engaged with and compresses a blank 12, the intermediate region 32 will generate a correspondingly shaped “medium” gauge region 40. It may be desirable, for at least some embodiments, that the length L_(ITR) and width W_(ITR) of the intermediate region 34 be sufficiently sized to ensure that the medium gauge region 40 covers a sufficiently sized portion of the workpiece 12 to exhibit isotropic properties, rather than being a mere discrete indentation or surface texturization exhibiting anisotropic properties.

The individual regions of the OD surface 28 of FIG. 1 are arranged such that the outermost, intermediate and innermost regions 30, 32, 34 sequentially press against and thereby modify the gauge of the metal workpiece 12. In so doing, the variable-radius (3D) metalworking roller 24 can introduce gauge differences into monolithic metal sheets without machining or welding. This, in turn, helps to provide a workpiece with isotropic properties, rather than additive manufacturing techniques that add or remove material, that may not provide isotropic properties, and may be undesirably slow. As can be seen in FIG. 1 of the drawings, the OD surface 28 of the roller 24 incorporates descending and ascending stepped segments 42 and 44, respectively, at leading and trailing edges, respectively, of the innermost valley region 34. The leading stepped segment 42 interconnects the innermost region 34 with the intermediate region 32, while the trailing stepped segment 44 interconnects the innermost region 34 with both the outermost region 30 and the intermediate region 32. A third stepped region (not visible in the views provided), which is descending with respect to the outermost region 30, interconnects the intermediate region 32 with the outermost region 30. Each stepped segment may be fabricated with round-chamfered edges at intersection points with the surface regions 30, 32, 34 to provide a gradual, rather than abrupt, change in gauge for the workpiece 12.

While aspects of the present disclosure have been described in detail with reference to the illustrated embodiments, those skilled in the art will recognize that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; any and all modifications, changes, and variations apparent from the foregoing descriptions are within the spirit and scope of the disclosure as defined in the appended claims. Moreover, the present concepts expressly include any and all combinations and subcombinations of the preceding elements and features. 

What is claimed:
 1. A metalworking roller for a rolling mill machine operable to modify a gauge of a metal workpiece, the rolling mill machine including a drive mechanism and a roll stand, the metalworking roller comprising: a cylindrical roller body configured to rotatably attach to the roll stand and drivingly connect to the drive mechanism, the roller body including an outer diameter surface spanning continuously around the circumference of the roller body, the outer diameter surface including an outermost peak region and an innermost valley region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body, wherein the outermost peak region and the innermost valley region are configured to sequentially press against and thereby modify the gauge of the metal workpiece.
 2. The metalworking roller of claim 1, wherein the innermost valley region has a first transverse width extending at least 30% of a longitudinal length of the cylindrical roller body.
 3. The metalworking roller of claim 2, wherein the innermost valley region has a first circumferential length extending at least 20% around the circumference of the cylindrical roller body.
 4. The metalworking roller of claim 2, wherein the innermost valley region has a first surface area and a first radial thickness constant along a length and a width of the first surface area.
 5. The metalworking roller of claim 1, wherein the outermost peak region has a second transverse width extending the entirety of a longitudinal length of the cylindrical roller body.
 6. The metalworking roller of claim 5, wherein the outermost peak region has a second circumferential length extending continuously around the entirety of the circumference of the cylindrical roller body.
 7. The metalworking roller of claim 7, wherein the outermost peak region has a second surface area and a second radial thickness constant along a length and a width of the second surface area.
 8. The metalworking roller of claim 1, wherein the outer diameter surface further includes an intermediate plain region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body, wherein the innermost valley region is recessed radially inward from the intermediate plain region.
 9. The metalworking roller of claim 8, wherein the intermediate plain region has a third transverse width extending at least 50% of a longitudinal length of the cylindrical roller body.
 10. The metalworking roller of claim 8, wherein the intermediate plain region has a third circumferential length extending at least 40% around the circumference of the cylindrical roller body.
 11. The metalworking roller of claim 8, wherein the intermediate plain region has a third surface area and a third radial thickness constant along a length and a width of the third surface area.
 12. The metalworking roller of claim 1, wherein the outer diameter surface further includes descending and ascending stepped segments at leading and trailing edges, respectively, of the innermost valley region, the descending and ascending stepped segments interconnecting the innermost valley region with the outermost peak region.
 13. The metalworking roller of claim 12, wherein the descending and ascending stepped segments each comprises round-chamfered edges at intersection points with the innermost valley region and the outermost peak region.
 14. A rolling mill machine for changing a gauge of a sheet metal workpiece, the rolling mill machine comprising: a roll stand; a drive mechanism operatively connected to the roll stand; a subjacent roller rotatably mounted to the roll stand; and a metalworking roller drivingly connected to the drive mechanism and rotatably mounted to the roll stand juxtaposed with the subjacent roller, the metalworking roller including a cylindrical roller body with an outer diameter surface spanning continuously around the circumference of the roller body, the outer diameter surface including an outermost peak region and an innermost valley region recessed radially inward from the outermost peak region, the outermost peak region and innermost valley region each having a respective surface area and a respective radial thickness constant along a length and a width of the respective surface area, wherein the outermost peak region and the innermost valley region are configured to sequentially press against and thereby reduce the gauge of the sheet metal workpiece to include first and second distinct gauges.
 15. A method of changing a gauge of a metal workpiece via a rolling mill machine with a metalworking roller rotatably mounted on a roll stand and drivingly connected to a drive mechanism of the rolling mill machine, the method comprising: feeding the metal workpiece into engagement with the metalworking roller, the metalworking roller including a cylindrical roller body with an outer diameter surface spanning continuously around the circumference of the roller body, the outer diameter surface including an outermost peak region and an innermost valley region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body; and rotating the metalworking roller via the drive mechanism such that the outermost peak region and the innermost valley region sequentially press against and thereby modify the gauge of the metal workpiece.
 16. The method of claim 15, wherein the innermost valley region has a first transverse width and a first circumferential length, the first transverse width extending at least 30% of a longitudinal length of the cylindrical roller body, and the first circumferential length extending at least 20% around the circumference of the cylindrical roller body.
 17. The method of claim 15, wherein the innermost valley region has a first surface area and a first radial thickness constant along a length and a width of the first surface area.
 18. The method of claim 15, wherein the outermost peak region has a second transverse width and a second circumferential length, the second transverse width extending the entirety of a longitudinal length of the cylindrical roller body, and the second circumferential length extending around the entirety of the circumference of the cylindrical roller body.
 19. The method of claim 15, wherein the outermost peak region has a second surface area and a second radial thickness constant along a length and a width of the second surface area.
 20. The method of claim 15, wherein the outer diameter surface further includes an intermediate plain region recessed radially inward from the outermost peak region and elongated circumferentially around the roller body, wherein the innermost valley region is recessed radially inward from the intermediate plain region. 